Compilare: user.cpp: In constructor ‘huffman::huffman()’: user.cpp:18:47: warning: converting to non-pointer type ‘long long unsigned int’ from NULL [-Wconversion-null] huffman() : lf(NULL), rg(NULL), times(NULL) {} ^ user.cpp: In function ‘int main()’: user.cpp:50:21: warning: unused variable ‘lf’ [-Wunused-variable] huffman *root, *lf, *rg, *now; ^ user.cpp:50:26: warning: unused variable ‘rg’ [-Wunused-variable] huffman *root, *lf, *rg, *now; ^